Ringmione seems to be the most popular hypothesis at the moment. It strikes me as extremely careless a plan for Harry to attempt; recall Quirrell's comments after the battle with the transfigured armor, and the first battle where passing out ended the transfiguration on the marshmallow he was practicing with.
However, I took "Harry's parents come to Hogwarts" as a completely insane move that Dumbledore/Macgonnagle would be highly unlikely to pull, and yet the elder wizards thought rather differently from me and did it anyway. I still think using the ring involves Harry assigning way too little cleverness to Dumbledore, but in light of the ordeal with his parents I'll give it a little more probability weight.
(Note also that Harry did something under the covers when Flitwick showed up.)
If Ringmione is true, then I would assign over 50% probability to Dumbledore having noticed it and not called out Harry on it, in the same way that Dumbledore appeared to have noticed Harry in Azkaban and chose to not reveal it. I suspect Dumbledore is still just fighting the War, and believes that Harry is the key to defeating Voldemort and/or actually is Voldemort, and so Dumbledore did not reveal Ringmione because he believes Harry is trying to do the right thing and revealing Ringmione would cause a disastrous confrontation.
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 94. The previous thread has passed 200 comments.
There is now a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
The first 5 discussion threads are on the main page under the harry_potter tag. Threads 6 and on (including this one) are in the discussion section using its separate tag system. Also: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22.
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: